Stripping blank spaces and newlines from strings in C

Question

I have some input like this:

"  aaaaa      bbb \n cccccc\n ddddd \neeee   "

And I need to sanitize it like this:

"aaaaa bbb cccccc ddddd neeee"

Basically:

• Trim all blank spaces at the beginning and end of the string
• Strip all new lines
• Strip all spaces when there is more than one, but always leave ONE space between words

Is there any easy way to do this or I'll have to process the string, char by char and copy the appropriate chars to a different variable?

Answer 1

Assuming you cannot modify string in place,

void splcpy(char *s, char *m){ //s is the unmodified string
  int word = -1; //keeps track what was stored in last loop
  while(*s){  //until it ends
    if(!isspace(*s)){
      if(word==0)  *m++ = ' '; //if last char was space, add space
      *m++ = *s++;
       word = 1;
    }
    else{
      if(word == 1)   word = 0; //if last char was !space
      while(isspace(*s++)); //consume all space until end
    }
  }
  *m = '\0'; //end the string nicely
}

---

char *input = "  aaaaa      bbb \n cccccc\n ddddd \neeee   ";
char *modified = malloc(sizeof(char) * strlen(input));

splcpy(input, modified);

Answer 2

You could use strtok to lexically tokenize the string, delimit with " \r\n\t". This will make your job easier.